It is often desired to sort objects based upon size characteristics. Sorting, if done by human operators, is very time consuming and labor intensive. Therefore, it is desirable to provide systems for automatically grading and sorting objects without the need of human intervention to provide lower labor costs, higher quality, and more uniform product grading.
Sorting systems in which the objects vary in size, shape, as well as orientation create additional problems in the grading process. For example, in the process of grading and sorting mushrooms, it is desirable to grade and sort based upon the diameter of the mushroom cap. Since the mushroom is composed of the cap and stem, various dimensions are presented to an automatic sort system which must be distinguished in order to properly grade a mushroom. Such an automatic system must therefore detect the difference between the mushroom cap and stem in order to properly detect various sizes of mushroom caps. Since the mushrooms in an automatic system will be oriented randomly, such as, for example, stem upwardly directed; cap upwardly directed; or both cap and stem visible, the system must perform grading independent of the orientation of the mushroom within the system.
A need has thus arisen for an automatic system for sorting randomly oriented objects of varying sizes, such as for example, mushrooms, into various categories of sizes. Such a system must provide for rapid throughput as well as for an accurate determination of object sizes independent of object orientation travelling through the system.